Warewasher sanitizer vented metering system

Abstract

A liquid sanitizing agent is drawn into a capillary conduit section of defined volume, then separated from the supply thereof by opening an atmospheric back pressure vent at the lower end of the capillary section at substantially the same time said capillary section is filled. The sanitizing agent in the capillary section is then pumped as a liquid plug of defined volume into the sanitizing system of the warewasher.

What is claimed is: 
     
       1. In combination with a warewasher such as a dishwashing machine having a sanitizing system for chemically sanitizing foodware items therein, including a dispenser which is operable for controllably delivering a liquid sanitizing agent from a supply thereof into the sanitizing system, a vented metering system comprising: (a) a conduit connecting the supply of the liquid sanitizing agent to the dispenser,   (b) means in said conduit forming a capillary section of defined volume, the upstream end of said capillary section being closest to the liquid sanitizing agent supply and above the supply,   (c) filling means for filling said capillary section with the liquid sanitizing agent,   (d) an atmospheric back pressure vent at the upstream end of said capillary section,   (e) holding and opening means for holding said atmospheric back pressure vent closed when said filling means is operated and until said capillary section is filled with the liquid sanitizing agent, and then opening said vent at substantially the same time that said capillary section is filled regardless of atmospheric conditions to separate the agent in said capillary section from the remainder of the agent in said conduit and provide a liquid plug of sanitizing agent of defined volume which is delivered into the sanitizing system.   
     
     
       2. The structure of claim 1 wherein said holding and opening means further comprises a timer for assuring that said capillary section is filled before said atmospheric back pressure vent is opened, said timer being connected for first operating said filling means for a predetermined time interval and holding said atmospheric back pressure vent closed during said timer interval, and then opening said vent, said timer interval being sufficient to fill said capillary section regardless of atmospheric conditions. 
     
     
       3. The structure of claim 1 wherein said filling means further comprises a pump connected to said conduit and forming part of the dispenser. 
     
     
       4. The structure of claim 3 wherein said pump comprises an air compressor and an air driven aspirator operably connected for aspirating and pumping the liquid sanitizing agent from the supply thereof through said conduit into the sanitizing system. 
     
     
       5. In combination with a warewasher such as a dishwashing machine having a sanitizing system for chemically sanitizing foodware items therein, including a dispenser which is operable for controllably pumping a liquid sanitizing agent from a supply thereof into the sanitizing system, a vented metering system comprising: (a) a conduit connecting the supply of the liquid sanitizing agent to the dispenser,   (b) means in said conduit forming a capillary section of defined volume, the upstream end of said capillary section being closest to the liquid sanitizing agent supply and above the supply;   (c) an air compressor and an air driven aspirator operably connected for filling said capillary section with the liquid sanitizing agent from the supply thereof and then pumping the liquid sanitizing agent from said capillary section into the sanitizing system,   (d) an atmospheric back pressure vent at the upstream end of said capillary section;   (e) timer means connected for first operating said air compressor and aspirator for a predetermined time interval and for holding said atmospheric back pressure vent closed during said time interval and until said capillary section is filled with the liquid sanitizing agent, said time interval being of a duration just long enough to fill said capillary section regardless of atmospheric conditions for assuring that said capillary section is filled, and then, at the end of said time interval, opening said atmospheric back pressure vent at substantially the same time that said capillary section is filled, the agent in said capillary section then being separated from the remainder of the agent in said conduit, and   (f) means for operating said air compressor and aspirator to pump the sanitizing agent in said capillary section as a liquid plug of defined volume into the sanitizing system.   
     
     
       6. A method for injecting a measured quantity of a liquid sanitizing agent into the sanitizing system of a warewasher such as a dishwashing machine having a sanitizing system for chemically sanitizing foodware items therein, including a dispenser which is operable for controllably delivering a liquid sanitizing agent from a supply thereof into the sanitizing system, comprising: (a) filling a capillary conduit section of defined volume with a liquid sanitizing agent drawn upwardly from a supply thereof,   (b) then venting the upstream end of said capillary section to atmosphere to separate the agent in the capillary section from that in the supply and provide a liquid plug of defined volume which is delivered into the sanitizing system wherein said venting occurs after the sanitizing agent is delivered into the capillary section from said supply for a predetermined time which is just long enough to fill the capillary section regardless of atmospheric conditions.   
     
     
       7. The method of claim 6 wherein said filling step is performed by aspirating the liquid sanitizing agent with an air driven aspirator.